1. Field of the Invention
This invention relates to instant-cooking noodles and to methods for the preparation of instant-cooking noodles using an efficient drying process which does not involve oil frying and can be entirely fat-free. These non-fried noodles are healthier than fat-fried noodles and possess both a desirable appearance and taste.
2. Description of the Background
Instant-cooking noodles are precooked and dried alimentary paste which, when immersed in boiling water, rehydrates within minutes to form edible products that can be used in soups and stews, or as side dishes or snacks. These quick-cooking noodles are typically purchased as a dried brick of noodles with spice packets that provide a desirable flavor and appearance to the resulting foodstuff.
One group of instant-cooking noodles are ramen noodles. Ramen noodles are prepared from alimentary paste which comprises wheat flour, salts and spices, but does not contain egg whites or egg solids. The absence of egg makes the dough difficult to work with and the dried noodles fairly fragile.
The most common method of preparing raw noodles is to pass the dough through shaped extrusion orifices. This is generally not possible with the large scale manufacture of ramen noodles. Extruded dough is typically too rigid and rehydrates poorly. Instead, ramen dough is sheeted or rolled into long flat layers which are sliced or cut into ribbons of noodles. The ribbons are steamed for short periods of time, cut to specified lengths and fried in, for example, palm oil or a combination of oils heated to between 125.degree. C. to 180.degree. C. for less than one minute. Frying imparts a desirable appearance and taste to the resulting noodle product. The noodles absorb a small amount of the oil which browns and gives the noodles a desirable fried flavor.
Fried noodles have a low moisture content which does not need to be reduced for extended storage. Noodle moisture content is between about 1% to 5% which allows for long term storage without the need for refrigeration. However, over time, oils within the noodles tend to oxidize. This oxidation produces a rancid odor and taste which, although not necessarily harmful, imparts a distinctive flavor to the product and limits its shelf life.
Several methods have been developed for the preparation of instant-cooking noodles which do not involve frying. In one method (U.S. Pat. No. 2,704,723), noodles are formed and precooked entirely with steam. However, using steam precooking, it is difficult to precisely determine when the noodles are adequately precooked. Starch within the noodles must be sufficiently gelatinized to achieve a discrete firmness and moisture content without being overcooked. The gelatinization process is referred to as alpha-conversion of the noodle starches. When water penetrates the noodle, the polymeric structure of the individual starch granules become hydrated and the noodles swell. When swelling is sufficient so that no crystallinity can be observed, the noodles have been sufficiently precooked. Ready-to-eat noodles have an alpha-conversion of around 85% (.+-.10%). The final alpha conversion occurs when the dried noodles are rehydrated with hot water.
Breakage or beta-conversion of the starch molecules occurs on overcooking. Oxidation of the oils also promotes beta-conversion. Overcooked noodles are limp and deteriorate. After a certain degree of beta-conversion has occurred, the noodles are no longer edible.
As a consequence of steam precooking, noodles have a high moisture content. However, to be shelf-stable, this moisture must be removed and a drying process added. The common shaped dough drying methods employ moderate temperatures and require many hours of drying to reduce the water content below 15% for packaging. Drying is performed by passes through warmed air ovens at temperatures of less than 65.degree. C. (U.S. Pat. No. 4,783,339). Many cycles of heating and cooling are often required. The costs associated with the additional time and space requirements necessary are considerable. Typical drying temperatures vary between about 45.degree. C. to about 110.degree. C., but temperatures as high as 130.degree. C. have sometimes been used (U.S. Pat. No. 4,234,617). Higher temperature drying has been shown not to be useful because noodle texture is compromised. The resulting product has a high degree of beta-conversion and becomes scorched imparting a burned flavor. Additionally, at these higher temperatures, noodles easily overcook as .alpha.-conversion rates cannot be satisfactorily controlled. Lower temperatures of between about 80.degree. C. to 110.degree. C. are preferred. However, temperatures below 80.degree. C. produce noodle shrinkage and reduce drying efficiency. Large drying storage units are required which greatly increases costs.
Conventionally air dried noodles still suffer from numerous additional drawbacks. The noodles themselves are unpleasing to the eye, having a washed out appearance, a rubbery mouth feel and, in the absence of oil, are bland and tasteless.
Methods that have addressed these problems have been directed at modifying the various components of the dough and their quantities. In U.S. Pat. No. 3,192,049, paste composition is adjusted to contain a small amount of a proteinaceous material such as soy flour or wheat gluten. These substances improve palatability and noodle texture. Although cooking times were shortened, noodle texture, taste and appearance were not improved. In U.S. Pat. No. 4,423,082, noodle dough was supplemented with a hydrolyzate of a starch derived from the root or the stem of a plant. The presence of the hydrolyzate starch increases the rate of water absorption and produces a more evenly precooked noodle in a shorter amount of time. Again, noodle texture was improved, but in the absence of oil, the product still had a washed out taste and appearance. Also, the dough itself was difficult to handle during manufacturing and individual noodles blistered and cracked when dried so there was a significant amount of waste.
A similar method, described in U.S. Pat. No. 4,230,735, uses a modification of this process whereby a fat or oil is substituted for the added starch. The drawbacks associated with non-fried noodles are somewhat overcome in that noodle taste is improved, however, fat content is very high, higher in most cases than traditionally fried noodles. In addition, due to the presence of the oil, drying is a lengthy process requiring many hours at moderate temperatures (30.degree.-60.degree. C.). Higher temperatures cannot be used because the rate of oil or fat oxidation increases, shortening product shelf life by producing undesirable odors.
In another non-frying process, noodles are coated with edible oil emulsifiers prior to steaming (U.S. Pat. No. 4,098,906). This technique achieves a noodle product which is similar to the fried noodle, but without frying. Noodles have the fried or oily taste which is organoleptically pleasing, and the texture to withstand the drying process without blistering or cracking. However, most of the negative aspects of frying are retained as well. The fat content of the resulting foodstuff is fairly high. Rancidity and cooking difficulties remained as problems.
Another process which attempts to overcome problems associated with drying requires precooking of the noodles in super-heated steam. Noodle precooking times are reduced and noodles can be rapidly dried in blowing air at between 35.degree. C. to 65.degree. C. Noodle surfaces have an increased evaporation rate. Warmed air blown on the noodles reduces noodles moisture content below 15% in minutes. Although rapid, the overall process is somewhat inefficient as condensation instantly forms on noodle surfaces after precooking. This initially raises the moisture content of the noodles higher than occurs with conventionally steamed noodles. The extra moisture must be eliminated before the moisture content of the noodle can be lowered. Super-heated steam is also somewhat dangerous and expensive to produce and utilize. Further, product flavor and palatability are not improved and noodles produced are rubbery and tasteless. Only when oil is added as a component or an emulsion does noodle flavor become acceptable (U.S. Pat. No. 4,098,906).
An alternative approach has been used wherein the dough is produced as a web, and dried in a two step process (U.S. Pat. Nos. 4,243,689 and 4,370,352). With this method, noodle dough is passed through a large die extruder under pressure forming a web. The web is steamed to produce .alpha.-conversion of the starch components. After steaming, the web is subjected to a preliminary drying step during which the water content of the web is reduced to below 35%. After preliminary drying, the web is cut into the desired noodle shapes and finally dried. These noodles are stated to have a more uniform .alpha.-conversion of the starch components and a reduced tendency to stick together during production. Noodle quality may be significantly increased, but a two step process is time consuming and fairly labor intensive. Multiple drying apparatuses must be included in an assembly line for any large scale production which greatly increases costs.